Compositions and methods for whitening teeth

ABSTRACT

Compositions and methods for whitening the teeth of a patient or subject are described for performing a dental prophylaxis or cleaning procedure during which at least one tooth whitening composition is applied to the surface of a stained tooth, said compositions and methods resulting in a tooth color change that is noticeable to the patient or subject immediately following the procedure. The novel procedure allows for a high degree of tooth whitening to be safely achieved in a short period of time while under the control of a dentist, dental hygienist, or other dental professional, and which at least partially coincides with the performance of a dental prophylaxis or cleaning procedure in order to save significant clinical operatory chair time compared to cleaning and whitening procedures that are performed in non-overlapping time frames or appointments. Light may also be used to enhance whitening.

BACKGROUND OF THE INVENTION

As the connections between healthy teeth and gums, and general overall health, have become increasingly evident in the past 100 years, oral care has become an important part of people's daily health maintenance regimens. In the process, a healthy looking smile has become representative of one's level of personal grooming and even social status, with straight, white and well shaped teeth being promoted in advertising and by cosmetic dentists as an integral part of one's self-image. Over the past 20 years, the availability of tooth whitening products and services has exploded in the marketplace, ranging from low priced over-the-counter (OTC) self-applied trays, strips, pens, mouthwashes and toothpastes, to expensive professionally applied or monitored products and procedures capable of effectively whitening teeth in as little as 45 minutes. In general, professionally applied products and services administered to a patient in a dental office or other clinical setting are seen to achieve the best teeth whitening results in the shortest amount of time. This is primarily due to the concentration of active ingredient, usually hydrogen peroxide or a hydrogen peroxide precursor, found in professionally applied whitening compositions. Such high concentrations, typically above 15% hydrogen peroxide by weight and often as high as 50% hydrogen peroxide by weight, can only be safely administered in a controlled setting where a professionally trained individual can isolate soft tissues from contact with these highly oxidative compositions. Frequent monitoring of a patient's progress over, for instance, a one-hour period is also critical in maintaining a high degree of safety when working with such high hydrogen peroxide concentrations. Optionally, light or heat energy may be applied in conjunction with these strong oxidizing compositions, in order to accelerate the process beyond that which is possible using just the compositions on their own. In general, these professionally-monitored products and services applied in a dental office or clinic will be referred to collectively as in-office or chairside whitening procedures.

Chairside whitening procedures are generally performed during a dental appointment scheduled specifically for the purpose of whitening the patient's teeth, or as an adjunct following a professional teeth cleaning, formally known as a dental prophylaxis or “prophy”. When tooth whitening is conducted immediately following a prophy, the total amount of time that the patient must remain in a dental chair can often exceed two hours.

A professional tooth cleaning is recommended by the American Dental Association as a means to prevent gum disease. Gum disease, or periodontitis, is the primary cause of tooth loss in adults over the age of 40. Gum disease has also been linked to other health problems, such as heart disease, osteoporosis, respiratory diseases, and other more serious systemic diseases. According to the Center for Disease Control and Prevention, approximately 68% of adults in the United States have at least one professional tooth cleaning annually (2008). There is speculation as to the reasons why so many adults neglect the benefits obtainable from regular tooth cleanings, ranging from lack of health insurance to the fear of dental procedures. Lack of patient knowledge is a problem that can be managed, however studies have shown that better education of patients only leads to modest changes in behavior and attitudes towards preventative dentistry.

In general, a typical teeth cleaning dental appointment comprises the following procedural steps:

-   -   (1) A dental hygienist or dental assistant may or may not take         x-rays of a patient's teeth.     -   (2) The dental hygienist or dental assistant will generally take         between 15 and 60 minutes to work on the teeth and gums (the         exact time depending upon both the amount of accumulation         present, as well as the teeth cleaning method chosen), using a         variety of tools, including manual or ultrasonic scalers to         remove the tartar and plaque from the patient's teeth.     -   (3) The hygienist will then floss between the teeth and         generally complete the cleaning procedure by polishing the front         (buccal) and back (lingual) surfaces of the teeth with an         abrasive composition known as a prophylaxis (“prophy”) paste.         Tooth polishing leaves a smooth tooth surface that is more         resistant to the adhesion and buildup of dental plaque between         dental cleaning appointments.

Despite the apparent benefits of preventative teeth cleaning as described above, nearly 80% of the population has some form of gum disease ranging from early stage gingivitis to advanced periodontitis. Symptoms of gum disease may include one or more of the following: bleeding gums, halitosis (bad breath), bad taste in the mouth, tooth sensitivity, sore gums, loose adult teeth, abscessed teeth or gums pulling away from the teeth, changes in the way the teeth fit together or dentures fitting poorly, exudates between the gums and teeth, sores in the mouth, and actual tooth loss. Such a high rate of chronic or acute gum disease indicates a low level of compliance when it comes to scheduling of a regular dental cleaning, and any means of increasing such compliance would clearly be beneficial to the patient's general oral health.

BRIEF DESCRIPTION OF THE INVENTION

The inventive tooth cleaning and whitening method comprises novel compositions and procedural steps that allow for the simultaneous performance of a dental prophylaxis and tooth whitening procedure. The procedure involves steps performed at least partially in parallel or contemporaneously with a typical dental prophylaxis procedure during which a significant amount of plaque, tartar and acquired pellicle are removed. In general, these steps may include, but are not limited to, chemical, mechanical and/or chemomechanical tooth surface conditioning, contact or impregnation of one or more teeth with a catalyst, contact or impregnation of one or more teeth with an oxidizing agent, exposure of one or more teeth to actinic energy comprising heat, light, sound, ultrasound, air or mechanical pressure (and combinations thereof), and contact or impregnation of one or more teeth with a tooth remineralizing, opacifying or pigmenting composition. Combinations of the above procedural steps have been developed that accomplish significant whitening of stained teeth in less than about 90 minutes when performed in conjunction with or during a dental prophylaxis procedure.

The ability of the inventive compositions and methods to simultaneously whiten teeth in parallel with a dental cleaning procedure is highly dependent upon the ability of the oxidizing agent to penetrate into tooth enamel and dentin. Both tooth enamel and dentin are composite structures comprising both organic and inorganic phases as well as interstitial spaces that are occupied by fluid. These interstitial spaces can accommodate fluid movement, which is generally in an outward direction, in other words from the interior of the tooth towards the enamel surface. However, fluids and other materials in contact with the enamel surface can influence fluid movement through tooth enamel and dentin with concentration gradients and/or capillary action, as well as in conjunction with pressure, heat, light and other external physical forces that can change the dynamic relationship between the tooth and the fluid in contact with the tooth.

Mathematical models have been constructed to predict the ability of fluids to penetrate into porous substrates. The Lucas-Washburn equation is one such method of developing a comparative “Penetration Coefficient” for various fluids, based on their viscosity, surface tension (with air) and contact angle (with a porous substrate). The model assumes that the porous solid is a bundle of open capillaries, so in other words the Penetration Coefficient is a comparative predictor of capillary flow rate. The Lucas-Washburn equation

$d^{2} = {\left( \frac{\gamma \; \cos \; \theta}{2\eta} \right){rt}}$

predicts the distance (d) traveled by a liquid in a porous substrate, where the liquid has a surface tension (γ) with air, a contact angle (θ) with the porous substrate surface and a dynamic viscosity (η), and where (r) is the capillary pore radius and (t) is the penetration time. The bracketed component of the Lucas-Washburn equation is the Penetration Coefficient, expressed as centimeters per second

${PC} = \frac{\gamma \; \cos \; \theta}{2\eta}$

The Lucas-Washburn equation predicts that the higher the PC, the faster a liquid will penetrate into a given porous capillary substrate. This means that, at least in theory, a high PC can be achieved for liquids with low viscosities, particularly for compositions also having a low contact angle (which is often, but not always, associated with a liquid having a low surface tension that will lead to efficient wetting of the porous substrate.

Penetration coefficients have been used recently to design improved dental materials, specifically sealants and low-viscosity composites intended to arrest the progression of carious lesions (Paris, et al, Penetration Coefficients of Commercially Available and Experimental Composites Intended to Infiltrate Enamel Carious Lesions, Dental Materials 23 (2007), pages 742-748. The authors show that low viscosity materials with high Penetration Coefficients (>50 cm/s) are capable of penetrating enamel carious lesions better than materials with low PCs (see corresponding patent application US 2006/0264532).

Prior art tooth whitening compositions have generally been formulated to have high viscosities for better retention in dental trays during the bleaching process, which prevents migration of the whitening composition from the tray due to salivary dilution. Moderate to high viscosities have also been the norm for chairside whitening procedures in order to prevent the whitening composition from migrating away from the tooth enamel surface. According to the Lucas-Washburn equation, moderate to high viscosity tooth whitening compositions (greater than about 100 centipoise at 25 deg C) will have low Penetration Coefficients and thus be predicted to have restricted movement into the whitening target, that is, the porous enamel substrate. It would thus be advantageous to design a tooth whitening carrier composition comprising an oxidizing agent with a low viscosity (<100 cps) and a high Penetration Coefficient (>50 cm/s) in order to achieve rapid penetration into tooth enamel and dentin.

Other factors affecting the ability of a liquid penetrant to infiltrate enamel and dentin are (1) surface charge effects (which is related to pH of the micro environment within the tooth, as well as the pH and counter ion content of the liquid penetrant), (2) adhesion of the liquid penetrant to the tooth surface (which is related to the surface tension and wetting ability of the liquid penetrant), and (3) osmotic effects (which are related to the direction of diffusion of the interstitial fluid in the tooth structure in relation to the liquid penetrant in contact with the tooth). Under certain circumstances, tooth whitening composition having viscosities in excess of 100 cps are contemplated, for instance when auxiliary means of increasing the penetration rate are available. For example, a tooth whitening composition with a viscosity between 5,000 and 100,000 cps can be utilized if heat and/or light and/or vibrational energy is used to increase the penetration rate of the composition into the tooth enamel structure. Various means of achieving viscosities in excess of 100 cps are contemplated, including the addition of one or more thickening agents comprising water-resistant polymers.

In general, one aspect of the inventive simultaneous tooth cleaning and whitening method comprises the following steps, preferably performed in a sequence of steps comprising:

-   -   applying an oxidizing composition to the surfaces of the teeth         to be whitened; and     -   performing a dental cleaning or hygiene procedure while the         oxidizing composition is in contact with the teeth to be         whitened.

In another aspect of the invention, a method for simultaneously cleaning and whitening teeth comprises the steps of:

-   -   removing the acquired pellicle by chemical, mechanical or         chemo-mechanical means;     -   applying an oxidizing composition to the surfaces of the teeth         to be whitened; and     -   applying a sealant composition over the oxidizing composition to         protect it from moisture in the oral cavity.

In yet another aspect of the invention, a two-component tooth whitening composition comprises:

-   -   an oxidizing composition comprising a fluid carrier, an         oxidizing agent, and a water-resistant polymer; and     -   a sealant composition comprising a volatile solvent and a         water-resistant polymer, wherein the oxidizing composition and         the sealant composition are combined on the tooth surface during         use.

In yet another aspect of the invention, a two-component tooth whitening composition comprises:

-   -   an oxidizing composition comprising a fluid carrier, an         oxidizing agent, and a water-resistant polymer; and     -   a sealant composition comprising a volatile solvent, an         oxidizing agent activator and a water-resistant polymer, wherein         the oxidizing composition and the sealant composition are         combined on the tooth surface during use.

In yet another aspect of the invention, a method for simultaneously cleaning and whitening teeth comprises the steps of:

-   -   applying a conditioning composition to the teeth surface;     -   applying an oxidizing composition to the teeth surface;     -   applying a sealant composition to the teeth surface;     -   cleaning the teeth surface;     -   polishing the teeth surface; and     -   removing the compositions from the teeth.

In yet another aspect of the invention, a method for simultaneously cleaning and whitening teeth comprises the steps of:

-   -   applying a composition to the teeth surface, wherein said         composition is comprised of at least a fluid carrier, a tooth         conditioner, an oxidizing agent and a water-resistant polymer,     -   cleaning said teeth surface;     -   polishing said teeth surface; and     -   removing said composition.

There is typically an extensive amount of scraping, scaling, and other modes of plaque and tartar removal performed during a dental cleaning or prophylaxis. During the cleaning procedure, the patient's mouth is usually open for an extended period of time during which excess saliva may accumulate in the oral cavity and come in contact with the tooth surfaces. Also, the patient is typically asked to rinse with water or a mouthwash at various times during the cleaning procedure in order to clear debris (plaque, tartar, blood, saliva, etc) from the oral cavity that accumulates from the cleaning process. It has been found that in order to achieve a desirable (that is, a noticeable) level of tooth whitening during said dental cleaning or prophylaxis, it is advantageous to prevent moisture from saliva or external sources (such as the rinsing solutions referred to above) from directly contacting the tooth surfaces that have been previously contacted with the oxidizing composition. By creating a barrier between extraneous moisture and the oxidizing composition, said moisture is prevented or limited in its ability to remove, dilute, neutralize or otherwise decrease the effectiveness of the oxidizing composition during the cleaning procedure.

One means of limiting the contact of external moisture with the oxidizing composition is to utilize an oxidizing composition having hydrophobic (“water-repelling”) properties when in contact with the tooth surface. Such hydrophobic properties can be imparted through the addition of one or more water-resistant or water-insoluble polymers, which may optionally provide a thickening function.

An alternative means of preventing moisture contamination of the oxidizing composition on the tooth surface is to cover the oxidizing composition with a film of water-insoluble or water-resistance material. Such materials may include, but are not limited to, polymer films and water-resistant or water-insoluble fluids, gels, creams, waxes and solids.

Yet another alternative means of preventing moisture contamination of the oxidizing composition on the tooth surface is to cover the oxidizing composition with a curable composition that can be converted from a liquid or gel into a higher viscosity liquid, gel or solid upon exposure to an external source of energy. Said external energy source may be electromagnetic or light energy, sound or ultrasound energy, mechanical or vibrational energy, electrical energy, or combinations thereof.

A preferred tooth cleaning and whitening method comprises the following steps:

-   -   1) Placing a check and lip retraction means into the oral cavity         of a subject. Said means may include a cheek retractor and/or         cotton rolls placed in such a way as to prevent the soft tissue         of the inside of the lips and checks from coming into contact         with the tooth surfaces;     -   2) Conditioning of the teeth surfaces to be whitened with a         conditioning agent or conditioning composition, using chemical,         mechanical, or chemo-mechanical means;     -   3) Contacting the conditioned tooth surfaces with one or more         compositions comprising an oxidizing agent;     -   4) Contacting the tooth surfaces with a water-resistant coating         or film-forming composition to protect the oxidizing agent from         direct contact with external moisture during the tooth cleaning         process;     -   5) Cleaning and scaling of subject's teeth in proximity to the         gum line, gingival margins and crevicular spaces while the         compositions of steps (3) and (4) above are in contact with the         tooth surfaces;     -   6) Polishing the teeth with prophylaxis or polishing paste         following completion of step (5);     -   7) Optionally repeating steps (3) and (4); and     -   8) Cleaning and rinsing all residual materials from tooth and         gum surfaces that were applied or produced during the         performance of steps (1) through (7).

Modifications to the axove procedure are possible and are some cases preferable. For instance, the conditioning agent or conditioning composition may be combined with the oxidizing composition of step (3) in order to reduce the amount of time required to perform the combined cleaning and whitening procedure. Also, water-resistant properties may be imparted to the oxidizing composition of step (3) in order to obviate the need for a separate step (4). Therefore, it is contemplated, but not required, that the compositions and/or agents of steps (2), (3) and (4) may be combined into a single composition (a) prior to packaging, (b) just prior to use, or (c) on the tooth surface during use. Optionally, a tooth-desensitizing agent, such as potassium nitrate, may be applied before, during, or alter any of the steps outlined above. Such a tooth-desensitizing agent may be applied as a stand-alone formulation or combined with the conditioning agent, oxidizing agent, water-resistant or film-forming composition, or any combination of these.

It is also contemplated within the scope of this invention to employ light energy and/or heat energy to accelerate the tooth whitening process through various means such as increasing the rate of oxidizing composition penetration into enamel and dentin, increasing the susceptibility of tooth stain chromogens to oxidation, and accelerating the oxidation process through advanced oxidation processes such as the photo-Fenton reaction. An added benefit of employing light energy, particularly that in the blue region of the light spectrum (approximately 400-500 nanometers), during the inventive simultaneous tooth cleaning and whitening process, is observed by the attenuation and/or killing of periodontal pathogens within the light energy exposure field. A particularly useful benefit realized by reducing the viability of periodontal pathogens prior to, during and/or after a tooth cleaning is the reduction in risk associated with a lower bacterial burden during a moderately invasive procedure (tooth cleaning) that can sometimes involve bleeding. Reduction of the available numbers and types of oral pathogens during a tooth cleaning process may be of significant benefit to the subject's overall oral and whole body health, since the association between the presence of periodontal pathogens, such as the black pigmented bacteria species Fusobacterium nucleatum and Porphyromonas gingivalis, and the incidence of systemic diseases (such as heart disease) has been shown in recent years to be quite strong. Light energy employed in the initial steps of the present inventive method is seen to be most beneficial, since pathogen reduction prior to the invasive cleaning process would occur. However, light energy applied at any point in time during the cleaning and whitening process can be of significant benefit to the patient's gingival and periodontal health.

Particularly useful is light energy having the following characteristics: wavelengths of between 380 and 700 nanometers (nm), between 400 and 500 nm, and between 410 and 460 nm; and light intensity (measured at the target surface, for example the tooth or gum surfaces, in terms of power density) of between 100 and 5,000 milliwatts per centimeter squared (mW/cm²), between 100 and 2,000 mW/cm², between 500 and 1,500 mW/cm², and between 100 and 300 mW/cm². Light sources such as light emitting diodes (LEDs), quartz halogen bulbs, tungsten halogen bulbs, plasma arc bulbs, and xenon flash lamps, to name a few, are contemplated to have utility in the present invention. Preferred light sources are LEDs with emission peaks between 400 and 500 nanometers.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects of the invention will be better understood from the detailed description of its preferred embodiments which follows below, when taken in conjunction with the accompanying drawings, in which like numerals and letters refer to like features throughout. The following is a brief identification of the drawing figures used in the accompanying detailed description.

FIG. 1 is a schematic depiction of an over molded lens that can be attached to a hand-held dental curing lamp for enhancing whitening in accordance with one aspect of the present invention.

FIG. 2 is an isometric view of the over molded lens shown in FIG. 1.

FIG. 3 is a schematic depiction of a brush-type applicator device for applying compositions to one or more teeth surfaces in accordance with certain method aspects of the present invention.

FIG. 4 depicts the applicator device shown in FIG. 3 in a reservoir of a composition such as those described herein prior to application of the composition to one or more teeth surfaces using the applicator device.

FIG. 5 is a schematic depiction of a pen-type applicator device holding a composition for application to one or more teeth surfaces in accordance with certain method aspects of the present invention.

FIG. 6 is a schematic depiction of an applicator device with a flexible reservoir holding a composition that can be squeezed from the reservoir into an applicator component for application to one or more teeth surfaces in accordance with certain method aspects of the present invention.

FIG. 7 is a schematic depiction of an alternate embodiment of a pen-type applicator device holding a composition in a porous solid for application to one or more teeth surfaces by a porous solid applicator component in accordance with certain method aspects of the present invention.

Those skilled in the art will readily understand that the drawings in some instances may not be strictly to scale and that they may further be schematic in nature, but nevertheless will find them sufficient, when taken with the detailed descriptions of preferred embodiments that follow, to make and use the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The compositions of the present invention are designed to provide a fast and effective means of whitening the teeth during the performance of a dental cleaning or prophylaxis. Various combinations of tooth conditioning compositions, oxidizing compositions and sealant compositions are envisaged to have utility in the practice of the inventive method, and the properties of these individual compositions may be combined into a single composition for ease of use and application. Alternatively, a tooth conditioning function may be combined with an oxidizing function into a single composition. Another alternative is to combine a tooth sealing function with an oxidizing function to reduce the number of application steps. Yet another alternative is to utilize a water-resistant oxidizing composition and a separate water-resistant sealant composition that are applied in sequence onto the tooth or teeth surfaces to be whitened.

The tooth conditioning composition may comprise a fluid carrier and one or more tooth conditioning ingredients. Fluid carriers include water, ethanol, diethyl ether, methoxypropane (methyl propyl ether), dimethyl isosorbide and combinations thereof. The tooth conditioning function, that is the ingredient or ingredients that remove the acquired pellicle and subsequently open the enamel porosities for better penetration of the oxidizing composition, may be provided by ingredients having an acidic and/or calcium chelating capabilities. Useful acidic compounds include both inorganic and organic acids such as phosphoric acid, hydrochloric acid, acetic acid, lactic acid, citric acid, and their salts. Useful calcium chelating compounds include both inorganic and organic chelating agents such as ethylenediaminetetraacetic acid (EDTA), phytic acid, 1-hydroxyethylidene-1,1′-diphosphonic acid, citric acid, and their salts. The tooth conditioning composition may also comprise a colorants and/or pigments to assist in the placement and application of the tooth conditioning composition onto the teeth during the combination whitening and cleaning procedure.

The oxidizing composition comprises a fluid carrier and an oxidizing agent. Fluid carriers include water, ethanol, diethyl ether, methoxypropane (methyl propyl ether), dimethyl isosorbide and combinations thereof. Oxidizing agents include peroxides, metal chlorites, percarbonates, perborates, peroxyacids, hypochlorites and combinations thereof. Preferred oxidizing agents are hydrogen peroxide, carbamide peroxide, poly (vinyl pyrrolidone)-hydrogen peroxide complex (Peroxydone®, ISP Corp, Wayne, N.J.), peroxyacetic acid, and sodium chlorite. The oxidizing composition preferably has a viscosity of less than about 100 centipoise and most preferably less than about 10 centipoise. The oxidizing composition may also comprise active components further related to the tooth whitening function (such as stabilizers, a secondary oxidizing agent, an oxidation catalyst, a pH-adjusting agent, and a calcium chelating agent), or to a non-tooth whitening function (such as remineralization of the tooth surface, prevention of tooth decay, tooth-desensitization, prevention of gingivitis and/or periodontal disease, and other diseases or conditions of the oral cavity). In addition, the oxidizing composition may comprise one or more colorants and/or pigments to assist in the placement and application of the sealant onto the teeth during the combination whitening and cleaning procedure. Such colorants and/or pigments may also be present to provide a stain masking effect that changes the appearance of the tooth while the oxidizing composition is in contact with the tooth surface during the procedure.

Preferred oxidation catalysts are chelated metal complexes, in particular complexes of iron and manganese. Particularly preferred chelated metal complexes are the family of tetraamido-N-macrocyclic ligand (TAML) iron catalysts described in U.S. Pat. Nos. 7,060,818, 6,241,779, 6,136,223, 6,100,394, 6,054,580, 6,099,586, 6,051,704, 6,011,152, 5,876,625, 5.853,428, and 5,847,120.

The oxidizing compositions of the present invention may also contain a surface active agent in order to lower the surface tension of the composition to provide for better wetting and adhesion of the liquid to the surface of the tooth. Anionic, cationic, non-ionic and zwitterionic surfactants are contemplated to have utility in providing the oxidizing compositions with a low surface tension. Preferred surfactants are sulfobetaines (such as amidosulfobetaine 3-16 and Lonzaine CS) and fluorosurfactants (such as Capstone 50 and Capstone FS-10).

Sealant compositions of the present invention may comprise a water-resistant polymer, copolymer or crosspolymer, and a fluid carrier. Hereinafter the term “polymer” and “polymers” shall be used to denote polymer(s), copolymer(s) or crosspolymer(s). Suitable water-resistant polymers include acrylate polymers, methacrylate polymers, modified cellulosic polymers, silicone polymers, urethane polymers, polyamide polymers, vinyl polymers, vinyl pyrrolidone polymers, maleic acid or itaconic acid polymers, and others. The water-resistant polymer should be soluble or dispersible in the fluid carrier. Particularly preferred polymers are poly (butyl methacrylate-co-(2-dimethylaminoethyl) methacrylate-co-methyl methacrylate), poly (ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethyl methacrylate chloride), ethylcellulose, and esterified or crosslinked poly (methyl vinyl ether-co-maleic anhydride). Additional preferred polymers are rosin derivatives such as the hydrogenated woods rosin resins available from Pinova, Inc (Brunswick, Ga.) sold under the trade names Foral AX, Foral DX and Foral NC. Other preferred polymers include hydrophobic block copolymers such as styrene-butadiene-styrene (SBS) copolymers, styrene-isoprene-styrene (SIS) copolymers, styrene-ethylene/butylene-styrene (SEBS) copolymers, and styrene-ethylene/propylene-styrene (SEPS) copolymers, all of which are available from Kraton Polymers US LLC, Houston, Tex. The fluid carrier may be a volatile solvent which will evaporate after contacting the sealant composition with the tooth surface, leaving behind a liquid or solid coating or film. Said solvent should have an evaporation rate equal to or greater than that of water, and preferably equal to or greater than that of butyl acetate. Suitable solvents include, but are not limited to, water, ethanol, diethyl ether, methoxypropane (methyl propyl ether), acetone, ethyl acetate, and other highly volatile solvents such as hexane, cyclohexane, heptane, and hexamethyldisiloxane. The sealant polymers listed above should be sufficiently soluble in the solvent or solvents chosen for a particular sealant formulation such that precipitation of the polymer does not occur during storage of the sealant composition. Suitable solvents for a sealant composition may be the same as, or different from, the solvents used in the accompanying oxidizing composition. Alternatively, suitable solvents for a sealant composition may be miscible with the solvents used in the accompanying oxidizing composition. Alternatively, suitable solvents for a sealant composition may be non-miscible with the solvents used in the accompanying oxidizing composition.

Alternatively, the sealant compositions may be curable liquids or gels, which are placed on the tooth surface and subsequently exposed to some form of activating energy which converts the liquid or gel sealant composition to a solid coating or film. Curable sealant compositions may also be chemically cured, whereby two or more components are combined just prior to use and placed on the tooth surface to cure, in other words, to change from a liquid or gel into a solid coating or film.

The sealant composition may also comprise active components related to a tooth whitening function (such as an oxidizing agent, an oxidation catalyst, a pH-adjusting agent, and a calcium chelating agent), or to a non-tooth whitening function (such as remineralization of the tooth surface, tooth-desensitization, prevention of tooth decay, prevention of gingivitis and/or periodontal disease, and other diseases or conditions of the oral cavity). In addition, the sealant composition may comprise one or more colorants and/or pigments to assist in the placement and application of the sealant onto the teeth during the combination whitening and cleaning procedure. Such colorants and/or pigments may also be present to provide a stain masking effect that changes the appearance of the tooth while the sealant composition is attached to the tooth surface in the form of a coating or film.

Sealant compositions comprising one or more activating components related to a tooth whitening function may be employed to catalyze or activate an oxidizing agent contained within an oxidizing composition previously applied to a tooth surface. An activating component improves the oxidizing power or effectiveness of an oxidizing agent, such that tooth stain chromogens are more effectively oxidized to less chromogenic molecular species. Activating components for a particular oxidizing agent may be specific to that oxidizing agent. For example, activating components for hydrogen peroxide include, but are not limited to, transition metal salts (such as ferrous gluconate), alkaline pH adjusting agents (such as ammonium, sodium, and potassium hydroxide), and peroxyacid precursors that react with hydrogen peroxide to form another oxidizing agent (such as glyceryl triacetate, which reacts with hydrogen peroxide to form peroxyacetic acid). Activating components for metal chlorites such as sodium chlorite include acidic pH adjusting agents. By applying a sealant composition comprising an activating component onto a tooth surface previously contacted with an oxidizing composition comprising an oxidizing agent, the oxidizing agent on or in the tooth surface becomes activated and is more effective at oxidizing tooth stain chromogens. The preferred method of application of an activating sealant comprises as a first step applying an oxidizing composition comprising an oxidizing agent to at least one tooth surface followed in sequence by a second step comprising the application of a sealant composition comprising an activating component for the oxidizing agent.

Compositions and methods that employ a sealant composition comprising an activating component are particularly useful at providing effective tooth whitening with non-peroxide oxidizing agents such as metal chlorites. In the European Community and elsewhere, regulations exist on maximum amount of hydrogen peroxide that may be used in oral care products. In such jurisdictions, other oxidizing agents or oxidizing agent precursors, such as sodium chlorite, are permitted for use in oral care products; however, the oxidizing power of these alternatives is limited. Activators for sodium chlorite, such as citric acid and other acidifying agents that are capable decreasing the pH of sodium chlorite in order to initiate the generation of the active oxidizing agent chlorine dioxide, are known and have been described in the prior art, for example U.S. Pat. Nos. 5,944,528 and 6,479,037.

The oxidizing and sealant compositions of the present invention may be applied by any number of means familiar to those skilled in the art, such as brushing, spraying, rubbing, or otherwise dispensing from a device or object designed to apply a liquid or solid to a tooth surface. Such means may include, but are not limited to, brushing, rubbing, spraying or otherwise applying said compositions to a tooth surface with sufficient precision to avoid, if desired, excess amounts of a composition from contacting the soft tissue surrounding or adjacent to the intended tooth surface target. Preferred applicators include brushes, felts, non-woven materials, foams (both open- and close-celled) and similar materials or constructions shaped in such a way as to provide good control of the composition during application onto one or more tooth surfaces. Preferred applicators are described in U.S. Pat. Nos. 5,829,976, 6,929,475, and 6,176,632; Patent Pubs. US2003/0232310A1, US2005/0026107A1; Oraceutical LLC's Patent Pub. US2014/0011163; and Int'l. Pub. WO2015/033262A2, all of which are incorporated herein by reference in their entirety.

Applicators may be single-use, disposable devices that are simply used to transfer a composition, stored in a separate container or reservoir, to a tooth surface. FIG. 3 schematically depicts an exemplary embodiment of a single-use applicator comprising a handle 15, preferably made of a suitable plastic material, with brush bristles 16 attached at one end of the handle 15. FIG. 4 shows the brush bristles 16 of the applicator submerged in a composition 17 held in a separate reservoir 18, which enables a user to pick up an amount of the composition 17 via the bristles 16 and thereafter transfer it to a tooth surface. The submersion and transfer steps may be repeated multiple times until the desired amount of the composition 17 has been applied to one or more tooth surfaces to implement inventive methods described herein.

Alternatively, applicators may be attached or otherwise connected to a reservoir containing a sufficient amount of a composition to provide for multiple applications of said composition to one or more tooth surfaces. FIG. 5 schematically depicts an exemplary embodiment of a pen-type applicator device comprising an applicator component 20 for applying a composition 21 to a tooth surface. The composition 21 is stored in a reservoir component 23 and a dispensing mechanism 24 is used to transfer said composition 21 from the reservoir component 23 to the applicator component 20. A connector component 25 provides a pathway for dispensing said composition 21 from the reservoir component 23 into the applicator component 20 by manually actuating the dispensing mechanism 24. A preferred applicator device is in the form of a pen 26 that houses the applicator component 20 (which in a preferred embodiment is a brush), the reservoir component 23 (containing the composition 21), the connector component 25, and the dispensing mechanism 24. In one preferred embodiment the dispensing mechanism 24 is a twist mechanism suitably constructed so that twisting it about the axis of the pen-type device 26 moves a piston axially of the device to extrude the composition 21 through the connector component 25 and into a proximal end of the applicator brush 20. Further actuation of the dispensing mechanism forces the composition to the distal end of the brush for application to a tooth surface (not shown). The applicator brush is depicted schematically in FIG. 5, but those skilled in the art will appreciate that it will preferably comprise bristles of a suitable material, such as nylon, polyester, polypropylene, or polyethylene, with spaces therebetween of dimensions that will hold the composition in place but permit it to be applied to teeth surfaces upon contact of the distal ends of the bristles with the teeth surfaces. In another preferred embodiment the dispensing mechanism can comprise a push-button arrangement that directly pushes a piston in the reservoir component axially whereby the composition 21 is forced through the connector component 25 and into the brush applicator component 20. It will be appreciated that the composition 21 on or in the brush component 20 may be conveniently applied to one or more tooth surfaces in a controlled manner. It is anticipated that multiple repetitions of the above dispensing and applying steps may be necessary to apply the required amount of a composition to one or more tooth surfaces, and such repeated applications are within the scope of the inventive methods described herein. The pen-type device further includes a cap 27 that snaps onto the pen housing to protect the brush and prevent inadvertent contact with it when the device is not in use.

Yet another type of applicator device is a unit-dose disposable assembly, shown schematically in FIG. 6, comprising an applicator component 26, a flexible or compressible reservoir 27 designed to contain a composition 28 for use in accordance with one or more methods of the present invention, a connector component 29 for providing a pathway for said composition 28 to be transferred from the reservoir component 27 to the applicator component 26. In this particular embodiment, manual or mechanical pressure is applied to the flexible or compressible reservoir 27 to squeeze together its opposing walls such that the composition 28 contained in the reservoir 27 is forced through the connector 29 into or onto the applicator, which in a preferred embodiment is a brush in accordance with the preceding description. Once the composition 28 is in or on the applicator component 26, it may be conveniently applied to one or more tooth surfaces in a controlled manner. It is anticipated that multiple repetitions of the above dispensing and applying steps may be necessary to apply the required amount of a composition to one or more tooth surfaces.

Yet another applicator device is a unit-dose or multiple use assembly, shown schematically in FIG. 7, comprising a porous solid or brush-type applicator component 30, a porous solid inner reservoir storage component 31, which stores a fluid composition 34 and is in direct contact with the porous solid or brush applicator component 30, and a reservoir housing component 32. Suitable porous solids may be made by fusing various size particles or fibers of polymers such as polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, polyester, ethyl vinyl acetate, polycarbonate, nylon, or polyurethane to create sintered solids with a range of densities and void volumes (the volume of open space between fused particles of polymer that can be occupied by a gas or liquid). Porous solid void volumes between about 30% and 70% (based on the total volume of the porous solid) and pore sizes between about 5 and 100 microns, are suitable for use in the present device. Porous solids such as those available from Porex Corporation (Fairburn, Ga.) and Essentra Porous Technologies (Colonial Heights, Va.) may be used as the porous solid applicator 30 and/or the porous solid reservoir 31 in the unit-dose or disposable device describe in this applicator example. For purposes of the present description, the term “porous solid” includes any solid material capable of absorbing a liquid composition in accordance with the present invention and transferring it by capillary action upon contact with another absorbent solid material or a solid surface such as a tooth surface. Accordingly, an applicator device according to this embodiment is particularly suited to storing and applying low viscosity compositions by dispensing them from the inner reservoir 31 and into the applicator component 30 via capillary flow.

Compositions with viscosities less than about 150 centipoise are advantageously stored and dispensed from a device comprising a porous solid applicator component in the form of a nib, such as those used in marker-type pens. Examples of such marker-type pens are found in the prior art, in particular those described in U.S. Pat. Nos. 3,231,924 and 5,909,978, both of which are incorporated herein by reference in their entirety. This type of applicator device will preferably include a cap 33 that attaches to the reservoir housing component 32 in such a way as to cover the applicator component 30 to prevent evaporative loss of the composition 34 during storage. The reservoir housing 32 may also contain a positioning member 36 for forcing the inner reservoir component 31 into direct contact with the applicator 30, which will facilitate capillary transfer or movement of the low viscosity composition from said reservoir storage component 31 to said applicator 30. Alternatively, the applicator 30 and reservoir storage component 31 may be a single component that is designed to provide both the application function and the storage function. This type of capillary flow applicator device provides a particularly preferred mechanism for transferring oxidizing and sealant compositions to a tooth surface in accordance with the present inventive methods. Since capillary flow of the oxidizing and sealant compositions will occur without the need for a dispensing force provided by one or more moving components actuated by the user (such as the twist or push-button mechanism of FIG. 5), this type of applicator device is preferred because it obviates the need for a separate dispensing actuation step and thereby saves time and motion on the part of the individual applying the compositions to teeth surfaces.

The applicator components described above may be permanently attached to the other device components or alternatively may be replaceable. The applicator component may also be permanently attached to a connector component, if present, as an integral assembly, and this applicator and connector assembly may be replaceable. Alternatively, the reservoir component may be replaceable or refillable with additional composition if needed. The entire applicator device may also be attached to a separate device that provides an additional source of energy, such as light or ultrasound. Said attachment may be permanent, wherein the applicator device and the energy-providing device are disposed of when the applicator device is empty. Alternatively, and preferably, said attachment may be temporary, wherein the applicator device, when empty, may be replaced with a new applicator device and the energy-producing device reused. In another variation, any of the applicator devices discussed above, and in particular those described in connection with FIGS. 3-7, can be adapted for use with the vibratory energy producing devices described in connection with FIGS. 1, 3, 7, and 8 of Oraceutical LLC's Patent Pub. US2014/0011163, which has been incorporated by reference herein.

The whitening and/or cleaning methods described herein may also be practiced by employing an additional source of energy to accelerate the oxidation process and further reduce the time needed to complete the procedure. External energy sources such as electromagnetic or light energy, sound or ultrasound energy, mechanical or vibrational energy, electrical energy, or combinations thereof may be advantageously employed at any point during procedures described herein to accelerate the whitening/cleaning process.

Contemplated within the scope of the present invention are compositions and methods for cleaning and whitening teeth in a home setting or otherwise outside of a dental office. Self-applied tooth whitening products are frequently chosen by users due to cost and convenience, but compared to professionally applied tooth whitening product, self-applied tooth whiteners generally demonstrate reduced effectiveness in terms of whitening speed and final results achieved. This is a result of the upper limit on the concentration of active ingredients, such as oxidizing agents that may be safely employed in a self-applied product not applied by a professional. If lower levels of active ingredients are present, then longer contact times with the tooth surfaces are required in order to achieve a satisfactory result. The compositions and methods of the present invention are well suited to provide long-term contact of oxidizing agents with tooth surfaces by reducing the ability of saliva to dissolve or dilute said oxidizing agents before they have a chance to oxidize tooth stain chromogens. Thus, the present inventive methods of applying the oxidizing and sealant compositions are well suited to self-application in a home setting or outside of a dental office.

Preferred oxidizing compositions for self-application comprise an oxidizing agent and a fluid carrier. Self-applied oxidizing compositions may also comprise a thickening agent, a water-insoluble or water-resistant polymer, a pH adjusting agent, a tooth conditioning agent and organoleptic modifiers such as a flavorants, sweeteners and colorants. Self-applied oxidizing compositions may be applied to the tooth surface using applicator devices such as those described elsewhere the present application.

Preferred sealant compositions for self-application comprise a water-resistant polymer and a fluid carrier. Self-applied sealant compositions may also comprise a thickening agent, an activator for accelerating the oxidizing agent upon contact with a tooth surface previously contact with a self-applied oxidizing composition, and organoleptic modifiers such as flavorants, sweeteners and colorants. Self-applied sealant compositions may be applied to the tooth surface using the applicator devices described elsewhere the present application.

Another preferred applicator device comprises two separate applicators connected to two separate reservoirs housed within a single reservoir housing of an applicator device. This type of device is convenient to the user in that both compositions are contained within the same device for ease of application and transport.

EXAMPLES

In order to achieve a significant degree of tooth whitening in an abbreviated time frame suitable for integration into the tooth cleaning (dental prophylaxis) process, ideal conditions for (1) oxidizer penetration into the tooth and (2) conversion of initial oxidizer form into active whitening species must be facilitated.

Time limitations are imposed on the additional steps required to achieve whitening during the tooth cleaning process by the realities of patient scheduling in the typical dental office, and such additional steps should not exceed 30 minutes beyond or in addition to the time required to perform a typical dental prophylaxis. Optimal conditions for penetration of an active whitening composition into tooth enamel must be present in order to reduce the amount of time and oxidizer concentration required to reach intrinsic stain depth. Important factors related to oxidizer penetration into the tooth are (1) the viscosity of the oxidizing composition, (2) the surface tension of the oxidizing composition and (3) the surface free energy (also called the critical surface tension) of the tooth surface.

The surface free energy of exposed tooth enamel is generally in the range of about 50-55 dynes/cm, however the acquired pellicle can lower this number significantly. In fact, one of the important functions of the acquired pellicle is to reduce the critical surface tension of the tooth surface in order to reduce the adhesion of bacteria. Liquid and gel compositions contacting the tooth surface penetrate into the tooth structure in relation to four primary factors: time, viscosity of the liquid or gel, surface tension of the liquid or gel, and surface free energy of the tooth at the point of contact.

The relationship of liquid surface tension to solid surface free energy, low contact angle (the tangential angle formed by a droplet deposited on a solid surface) and low viscosity, are all directly related to the Penetration Coefficient (as derived from the Lucas-Washburn equation) and must be optimized for the whitening composition to (1) rapidly wet the surface of tooth enamel and (2) penetrate the available porosities and channels through enamel as quickly as physically possible.

Example 1

The ability of various oxidizing compositions to penetrate intact enamel and dentin was determined as follows. Extracted molar and pre-molar teeth were obtained from orthodontists with patient consent and stored refrigerated in phosphate buffered saline (PBS) solution at pH 6.8 until use. In order to assess the ability of various liquid carrier fluids to penetrate tooth enamel, teeth were sectioned to remove their roots and a 3 mm diameter chamber was created in the center of the sectioned crown that was filled with PBS solution. The crowns were partially immersed (chamber with PBS solution facing up) in various liquid carrier fluids and a small (1 microliter) sample of the PBS solution was drawn every 60 seconds and placed on a peroxide test strip (EM Quant Strips 10337, EMI) Chemicals, a division of Merck SA, Darmstadt, Germany) to determine the amount of time required for hydrogen peroxide to penetrate the tooth enamel and dentin from the outer surface of the crown to the interior chamber containing PBS.

Oxidizing compositions in Table 1 below were prepared and stored in 20 ml glass vials until use.

TABLE 1 Percent (w/w) Ingredient 1A 1B 1C 1D 1E 1F 1G 1H 1I 1J 1K 1L Water 75.0 65.0 75.0 65.0   85.0 75.0 65.0 75.0 65.0 75.0 65.0  100.0 Ethanol 200 10.0 20.0 5.0 15.0 5.0 15.0 Diethyl ether 5.0 5.0 Methoxypropane 5.0 5.0 Acetone 10.0 20.0 Dimethyl isosorbide 10.0 20.0 Hydrogen peroxide 15.0 15.0 15.0 15.0   15.0 15.0 15.0 15.0 15.0 15.0 15.0   0.0 Adjusted to pH 4.0 with potassium hydroxide 0.1M Viscosity (cps @ 25 C.) <1 <1 <1 <1   1.3 <1 <1 <1 <1 1.5 1.5  1 Surface tension <40 <40 <40 <40 >50 <40 <40 <40 <40 <40 <40 >50 (dynes/cm) Contact angle (deg) <10 <10 <10 <10  30+ <10 <10 <10 <10 15 15  50+ PC (calculated) >100 >100 >100 >100 <50 >100 >100 >100 >100 >100 >100 <30 H₂O₂ detection (min) 13 12 12 10  20 14 12 14 14 15 16 ND* *ND = Not detected

Oxidizing compositions in Table 1 trended towards faster penetration of the tooth when both contact angle and viscosity of the composition was low (Examples 1A, 1B, 1C, 1D), 1F, 1G, 1H, 1J, and 1K). Oxidizing with high contact angles (greater than 30 degrees) did not seem to penetrate as well as those with contact angles less than about 10 degrees.

Example 2

The following multi-step process was developed to provide for rapid and effective whitening of the teeth during a dental cleaning procedure.

Step 1—Acquired Pellicle Removal

Facilitating oxidizer penetration into the tooth requires a thorough removal or modification of the acquired pellicle prior to contact with the oxidizer formulation. Therefore, whether integrated into a dental prophylaxis procedure or performed as a stand-alone process, the first step in the abbreviated whitening process (after determining a starting tooth shade) must be the removal of the acquired pellicle using chemical, mechanical or (preferably) chemo-mechanical means. Once the acquired pellicle has been removed, it is important that the “cleaned” tooth enamel surface has limited contact with the patient's saliva prior to application of the oxidizer composition (see Step 2) in order to prevent reformation of the pellicle film on the exposed enamel surface. Removal or modification of the acquired pellicle and optional micro-roughening of the exposed enamel surface will elevate the enamel surface free energy (preferably above about 60 dyne/cm), which promotes better wetting of the enamel surface by the oxidizing composition. Surface wetting is a key factor related to the speed at which a composition penetrates enamel, analogous to the effects of viscosity and surface tension on the penetration of bonding adhesives into conditioned enamel and sealants into caries lesions.

Step 1a

Placement of cheek retractor or other means of preventing contact of the lips and interior gum surfaces with the teeth.

Step 1b

Application of Conditioner for 30-60 seconds.

Tooth Conditioner Composition

Ingredient Percent (w/w) Water 90.0 Poly (methyl vinyl ether-co-maleic anhydride)* 10.0 *Gantrez S-95 (ISP Corp, Wayne, NJ) (hydrolyzed, pH 2.0)

Step 2—Oxidizer Contact and Penetration

Once the acquired pellicle has been removed, the teeth surfaces are contacted with a low viscosity oxidizer composition with a surface tension significantly lower than that of the surface free energy of the exposed enamel surface. A low viscosity oxidizing composition that has a low surface tension will have a very low contact angle when placed on the enamel surface and thus be better suited to penetrate into the enamel porosities. The oxidizer composition should comprise hydrogen peroxide in an aqueous form (or mixed with viscosity-reducing solvents) and at a concentration between about 1% and 30% by weight (higher amounts being contemplated in situations where precise control and placement of the oxidizing composition is possible). The oxidizing composition should also have a pH within a range similar to that reported for the isoelectric point of tooth enamel, which is between about 3.8 and 4.7, although higher pH levels are possible with oxidizing compositions comprising ionized species capable of counteracting the influence of charged components in tooth enamel. The oxidizing composition is brushed repeatedly onto the tooth surfaces to be whitened over the period of about 7-10 minutes to provide as much full strength hydrogen peroxide at the interface over the initial treatment phase.

Step 2a

Application of oxidizing composition to buccal and (optionally) lingual surfaces of teeth.

Oxidizer Composition

Example 1D

Step 3—Sealing Enamel Surface Prior to Dental Prophylaxis Procedure

In order to prevent dilution or removal of the oxidizing composition in or from the tooth enamel treated in accordance with Step 2 above, a water-resistant protective sealant is applied (and if solvent-based, allowed sufficient time for the carrier solvent to evaporate). The sealant composition may also comprise an additional oxidizing agent to provide an additional reservoir of whitening active, and/or an advanced oxidation catalyst in order to promote active oxidizing species such as hydroxyl radicals (.OH) and perhydroxyl anions (—OOH) and/or a desensitizing agent to reduce or eliminate any tooth sensitivity associated with the procedure.

Step 3a

Application of Sealant to buccal and (optionally) lingual surfaces of teeth

Sealant Composition

Ingredient Percent (w/w) Ethanol 200 proof 90.0 Poly (butyl methacrylate-co-(2-dimethylaminoethyl) 10.0 methacrylate-co-methyl methacrylate)* *Eudragit E100 or EPO (Evonik Rohm GmbH, Darmstadt, Germany)

The sealant composition is applied onto the surfaces of the teeth previously contacted with the oxidizing composition and allowed to fully dry before proceeding to Step 4.

Step 4—Performance of the Dental Prophylaxis Procedure

Following the sealing process, a dental prophylaxis is performed using standard protocols and materials. Care should be taken to avoid excessive disruption of the sealant on the buccal and lingual (if coated) surfaces of the teeth during the cleaning procedure. The dental prophylaxis is otherwise performed in a standard fashion, including polishing of the teeth with a standard prophy paste (which will remove the Sealant applied in Step 3). A final tooth shade may be taken at this time.

Step 5—Final Treatment

If time permits, Steps 2 and 3 are repeated after prophy cleanup. No further intervention is required to remove the Sealant if applied after completion of the dental prophylaxis and dismissal of the patient. The Sealant may remain in place after the patient leaves the office and will slowly erode over time. The patient may also be supplied with a home-use version of the oxidizing composition and the sealant as an option for continued improvement in tooth color.

The above steps were performed on extracted molars and premolars (n=25) obtained through orthodontists with patient consent and stored refrigerated in phosphate buffered saline (PBS) solution at pH 6.8 until use. Individual teeth were removed from the PBS solution, allowed to air dry for 60 seconds and the roots inserted up to the cementoenamel junction into a high viscosity aqueous gel to keep the roots hydrated during the procedure. An initial tooth shade was taken using a Minolta CM504i chromameter (Konica-Minolta) and recorded. Steps 2 (total treatment time of 10 minutes) and 3 (total treatment time of 120 seconds) were performed on the extracted teeth, and a 32 minute period was allowed to elapse during which the teeth were rinsed with water every 8 minutes to simulate the rinsing process that typically occurs during the cleaning process. After the simulated cleaning process time had elapsed, the teeth were polished with a medium grit prophy paste using a slow speed handpiece and prophy cup. Teeth were rinsed with water and a final tooth shade was taken using the method described above and recorded in Table 2 below (L, a, b=Initial color readings, L*, a*, b*=final color readings).

TABLE 2 Tooth L a b L* a* b* Delta L Delta a Delta b Delta E 1 76.10 3.14 15.98 78.11 1.61 13.13 2.01 −1.53 −2.85 3.81 2 76.90 3.44 12.45 80.98 2.40 13.01 4.08 −1.04 0.56 4.25 3 74.23 3.32 16.05 78.33 1.98 12.77 4.10 −1.34 −3.28 5.42 4 74.25 2.00 16.21 77.21 1.74 12.12 2.96 −0.26 −4.09 5.06 5 78.21 3.24 14.76 80.43 1.99 11.26 2.22 −1.25 −3.50 4.33 6 75.21 3.01 15.90 77.77 2.45 14.01 2.56 −0.56 −1.89 3.23 7 74.79 1.82 13.88 78.23 1.43 13.20 3.44 −0.39 −0.68 3.53 8 72.24 3.32 16.43 75.20 2.99 13.95 2.96 −0.33 −2.48 3.88 9 73.19 3.87 15.81 78.81 2.33 10.32 5.62 −1.54 −5.49 8.01 10 77.31 3.66 14.73 77.60 1.84 9.99 0.29 −1.82 −4.74 5.09 11 71.89 3.97 17.68 76.39 2.77 14.02 4.50 −1.20 −3.66 5.92 12 74.54 3.58 14.32 78.40 2.87 13.13 3.86 −0.71 −1.19 4.10 13 73.29 3.82 14.65 78.41 2.02 13.03 5.12 −1.80 −1.62 5.66 14 74.03 3.92 16.33 76.75 2.36 14.56 2.72 −1.56 −1.77 3.60 15 71.99 2.98 15.03 77.90 1.75 11.82 5.91 −1.23 −3.21 6.84 16 73.98 3.92 15.57 78.02 1.99 11.08 4.04 −1.93 −4.49 6.34 17 73.12 3.22 16.23 76.19 1.56 13.84 3.07 −1.66 −2.39 4.23 18 76.00 3.42 15.48 78.88 1.98 10.63 2.88 −1.44 −4.85 5.82 19 73.94 3.73 14.14 78.58 2.02 10.73 4.64 −1.71 −3.41 6.01 20 74.74 3.46 15.02 77.33 2.38 13.05 2.59 −1.08 −1.97 3.43 21 70.95 3.98 17.43 75.02 2.97 12.83 4.07 −1.01 −4.60 6.22 22 73.49 4.03 16.55 77.91 3.13 13.43 4.42 −0.90 −3.12 5.48 23 76.03 3.10 18.30 78.73 1.57 13.22 2.70 −1.53 −5.08 5.95 24 73.83 3.28 17.43 77.00 1.22 10.15 3.17 −2.06 −7.28 8.20 25 74.17 2.98 15.12 78.36 2.09 11.03 4.19 −0.89 −4.09 5.92 Average 73.84 3.46 16.03 77.63 2.06 11.98 3.79 −1.40 −4.04 5.72

Example 3

The following whitening method was used to demonstrate the ability of a high viscosity tooth whitening composition to remove an artificial stain from the surface of a bovine enamel substrate in vitro when light energy is used to enhance penetration.

Staining of Bovine Enamel Slabs

1. Substrates

-   -   a. 10 mm×10 mm bovine incisor (enamel) fragments mounted in         clear resin     -   b. 600 grit finished surface     -   c. Unsealed

2. Storage of Substrates

-   -   a. Always store substrates at 100% relative humidity, or at         4° C. in Double Distilled H₂O or Phosphate Buffered Saline         solution     -   b. Never allow substrates to fully dry out as surface will         change, dry only as part of staining procedure and never for         extended periods.

3. Staining Solution

-   -   a. 3 g of fine ground leaf Tea     -   b. 3 g of fine ground Coffee     -   c. 300 ml of boiling ddH₂O     -   d. Infuse for 10 min with stirring (use magnetic stirrer)     -   e. Filter solution through tea strainer with additional filter         paper     -   f. Cool to 37° C.

4. Preparation of Tooth Samples

-   -   a. Labelling: Label the bovine samples on one side of the resin         with permanent marker (to track the samples if using more than         one)     -   b. Rub the surface of the enamel with wet wipe and then grit         finish is on the wet surface with orbital motion covering the         whole surface for nearly 10 sec     -   c. Wash the surface with water and make it dry with Kimwipe     -   d. Sealing: Seal all the surfaces of the resin, excluding the         enamel surface of bovine fragment (i.e., all four sides and         bottom) with clear nail varnish     -   e. Leave it on bench top for air drying with the enamel surface         touching the bottom for 30-45 min     -   f. Etching: sequential immersion in 0.2 m HCl saturated Na₂CO₃,         1% Phytic Acid (30 seconds each) and finally rinse with double         distilled H₂O     -   g. Make it dry with Kimwipe and then they are ready for staining

5. L*a*b Measurement

-   -   Measurement before and after staining.

6. Staining Procedure

-   -   a. Prepare the staining broth (Section 3) and fill a glass         bottle with 200 ml of the broth     -   b. Keep the samples to be stained in the broth continuously for         four days     -   c. Tighten the cap of the bottle to ensure that the broth is not         evaporating from the bottle     -   d. Gently mix the broth every day to make sure that the         particles are not settling at the bottom of the bottle     -   e. After staining the samples, rinse substrate with Millipore         water (wipe it) and measure LAB values

Samples of the stained bovine enamel slabs were contacted with a tooth whitening composition shown in Table 3.

TABLE 3 Ingredient Percent Deionized water 35.40 Glycerin 20.00 Etidronic acid 0.30 Potassium stannate 0.10 Hydrogen peroxide 12.00 Carbopol 974P-NF 2.00 Sucralose 0.30 PEG-60 hydrogenated castor oil 3.00 Flavor 1.00 Ammonium Hydroxide 29% (to pH 5.0) 1.10 Total 100.00

The above composition is a transparent gel having a viscosity of approximately 10,000 cps @25 deg C and a pH of 5.0.

The tooth whitening composition of Table 3 was brushed on to the surfaces of stained bovine enamel slabs prepared as described above. Immediately after contacting the slabs with the tooth whitening composition, light energy was applied using a hand-held dental curing light with a high-powered LED emitting approximately 500 mW/cm² of blue light with a peak wavelength of approximately 450 nm. The hand-held curing light used a lens cup 10 depicted schematically in FIGS. 1 and 2 as having a lens 12 over which a thermoplastic elastomer cup 14 was molded to provide a mechanism for spacing the curing light energy L (represented notionally in FIG. 1) at the same distance from the surface of the bovine slab for each sample. The over molded cup forms a small chamber that controls the positioning and movement of the gel on the tooth surface, while simultaneously emitting light energy through the lens onto the tooth surface to accelerate the penetration of the tooth whitening composition into the tooth structure.

The resulting changes in L, a and b values, together with the composite delta E change in tooth color, is shown in Table 4 below.

TABLE 4 dL da db dE*ab tooth 1 8.15 −4.17 −6.17 11.04 tooth 2 6.91 −3.56 −5.71 9.65 tooth 3 2.69 −1.76 −5.18 6.09 tooth 4 5.53 −2.89 −2.45 6.71

As can be seen by the changes in L, a and b values, as well as the composite delta E value changes, significant tooth color changes may be effected by utilizing a high viscosity tooth whitening composition when combined with a high intensity light source adapted with a lens comprising an over molded thermoplastic elastomer spacer cup. It is anticipated that the inclusion of a light exposure step, as demonstrated in the Example, would be of significant advantage in improving the tooth whitening effect observed in Examples 1 and 2. Exposing the tooth surfaces and their surrounding soft tissue will also lead to an improvement in periodontal health through the reduction of periodontal pathogens such as black pigmented bacteria.

Example 4

The following Table 5 presents a representative range of oxidizing composition components and their concentrations found useful in the practice of the present invention.

TABLE 5 Oxidizing Composition Component Percent (w/w) Solvent 50-99 Oxidizing agent  1-50 Optional thickening agent 0.5-45  Optional water-resistant polymer  0.1-20.0 Optional surface active agent 0.01-5   Optional colorant 0.001-0.750 Optional flavorant 0.05-0.50 Optional photoactivating agent 0.01-2.00

Example 5

The following Table 6 presents a representative range of oxidizing composition components and their concentrations found useful in the practice of the present invention.

TABLE 6 Sealant Composition Component Percent (w/w) Solvent 60-99 Water-resistant polymer  1-50 Optional oxidation activating agent  0.01-10.00 Optional surface active agent 0.01-5   Optional colorant 0.001-0.750 Optional flavorant 0.05-0.50

Example 6

The following two-part tooth whitening composition was prepared and each part packaged into separate capillary flow type dispensing pens as described above in connection with FIG. 7.

Non-peroxide oxidizing composition Part A Ingredient Percent Deionized water 97.50 Sodium chlorite 2.50 Total 100.00

Sealant composition Part B Ingredient Percent Ethanol 77.50 Poly(ethyl acrylate-co-methyl methacrylate-co- 17.50 trimethylammonioethyl methacrylate chloride) 1:2:0.2 (Eudragit RL-PO) Citric acid anhydrous 5.00 Total 100.00

The two compositions are applied sequentially onto a stained tooth surface and thereby come into interfacial contact with subsequent mixing of the components. It is preferred that Part A be applied to the stained tooth surface first, followed by Part B. The sodium chlorite component of Part A, when contacted by the citric acid component of Part B, activates the sodium chlorite by acidification and subsequent conversion to chlorine dioxide.

SUMMARY

It will be understood that the embodiments of the invention described above can be modified in myriad ways other than those specifically discussed without departing from the scope of the invention. General variations to these embodiments may include different tooth whitening compositions, light sources, methods of applying compositions and/or light, and contact and/or exposure time of tooth whitening compositions and/or light on the tooth surface.

Those skilled in the art will readily recognize that only selected preferred embodiments of the invention have been depicted and described, and it will be understood that various changes and modifications can be made other than those specifically mentioned above without departing from the spirit and scope of the invention, which is defined solely by the claims that follow. 

What is claimed is:
 1. A tooth whitening method comprising: applying an oxidizing composition comprising a fluid carrier and an oxidizing agent to one or more teeth in an oral cavity; and thereafter applying a sealant composition to the one or more teeth to which the oxidizing composition was applied, wherein the sealant composition comprises a fluid carrier and a water resistant polymer that forms a coating that resists moisture contamination of the previously applied oxidizing agent. 